This invention relates to a novel composite flexure and a unique precision clamp incorporating a number of the composite flexures.
Flexures, generally stiff along their axis and flexible off axis are used in latches, clamps, and mounts and the like where it is desirable that the flexure bends without yielding but then springs back into its original position. Prior art flexures are typically unitary in construction made of spring steel or titanium, for example. Such flexures are also limited in thickness to provide the desired lateral flexibility and thus may suffer from reduced axial stiffness.
Composite materials are renowned for their high stiffness and strength to weight ratios, and low thermal expansion characteristics. Traditional components made of composite materials, however, do not readily flex or bend easily nor are they designed to do so.
Accordingly, to our knowledge, no one has taught or suggested the construction of a flexure made of composite materials. Such a flexure would be desirable because of its high axial stiffness, and low thermal expansion.
It is therefore an object of this invention to provide a flexure made of composite materials.
It is a further object of this invention to provide such a flexure which is lightweight and yet very stiff and has low thermal expansion.
It is a further object of this invention to provide a method of manufacturing such a composite flexure.
It is a further object of this invention to provide a latch or clamp incorporating composite flexures.
The invention results from the realization that a novel composite flexure which is stiff along its longitudinal axis but flexible off axis can be effected by purposefully delaminating adjacent plies at a preselected regions so they can move relative to each other when the flexure is subjected to bending loads.
This invention features a flexure comprising a plurality of plies of composite material consolidated everywhere except at at least one predefined region where preselected adjacent plies are purposefully delaminated so they can move relative to each other when the flexure is bent.
The plies are typically grouped together in a number of consolidated layers except at the predefined region where there is no consolidation between adjacent layers. In the preferred embodiment, there are a number of consolidated layers each including a plurality of plies except at the predefined region where there are less layers and no consolidation between adjacent layers.
The flexure is typically substantially longer than it is thick and substantially longer than it is wide. In one embodiment, the plies include axial carbon fibers embedded in a resin matrix. The method of manufacturing a flexure, in accordance with this invention, includes forming a plurality of composite plies into a number of layers; placing between two adjacent layers a non-impregnatable material at a predefined region therebetween which interrupts another layer disposed between the two adjacent layers; applying heat and pressure to consolidate all the layers except at the predefined region; and removing the non-impregnatable material.
The layers may include plies of axial carbon fibers embedded in a resin matrix and each layer is at least partially consolidated except the interrupted layer which may be a prepreg. One possible non-impregnatable material is a number of metallic shims. The flexure of this invention includes a number of plies of composite material consolidated everywhere except at at least one predefined region where preselected adjacent plies are purposefully delaminated so they can move relative to each other when the flexure is bent, the plies group together in a number of consolidated layers except at the predefined region where there is no consolidation between adjacent layers. A plurality of plies of composite material are consolidated everywhere except at at least one predefined region where preselected adjacent plies are purposely delaminated so that they can move relative to each other when the flexure is bent. The flexure includes a number of consolidated layers each including a plurality of plies except at the predefined region where there are less layers and no consolidation between adjacent layers.
The latch assembly of this invention includes a tang and a clamp which receives the tang. The clamp includes: a base; and at least two flexures extending from the base spaced from each other defining opposing jaws which, when flexed away from each other, accept the tang therebetween and which when released secure the tang in the clamp between the jaws. Each flexure typically includes a plurality of plies of composite material consolidated everywhere except at at least one predefined region where preselected adjacent plies are purposely delaminated so that they can move relative to each other when the flexure is bent. Each clamp jaw may include a number of flexures and may include an end cap secured to the terminal ends of the plurality of flexures. Typically, each clamp jaw includes at least two spaced flexures. Each clamp jaw may include two sets of spaced flexures. Each clamp jaw may include a bearing attached thereto. A spreader assembly may also be included to urge the jaws apart. The tang may also include flexures.